Semiconductor device and method of forming interposer frame over semiconductor die to provide vertical interconnect

ABSTRACT

A semiconductor device has a first semiconductor die mounted over a carrier. An interposer frame has an opening in the interposer frame and a plurality of conductive pillars formed over the interposer frame. The interposer is mounted over the carrier and first die with the conductive pillars disposed around the die. A cavity can be formed in the interposer frame to contain a portion of the first die. An encapsulant is deposited through the opening in the interposer frame over the carrier and first die. Alternatively, the encapsulant is deposited over the carrier and first die and the interposer frame is pressed against the encapsulant. Excess encapsulant exits through the opening in the interposer frame. The carrier is removed. An interconnect structure is formed over the encapsulant and first die. A second semiconductor die can be mounted over the first die or over the interposer frame.

FIELD OF THE INVENTION

The present invention relates in general to semiconductor devices and,more particularly, to a semiconductor device and method of forming aninterposer frame over a semiconductor die to provide vertical electricalinterconnect.

BACKGROUND OF THE INVENTION

Semiconductor devices are commonly found in modern electronic products.Semiconductor devices vary in the number and density of electricalcomponents. Discrete semiconductor devices generally contain one type ofelectrical component, e.g., light emitting diode (LED), small signaltransistor, resistor, capacitor, inductor, and power metal oxidesemiconductor field effect transistor (MOSFET). Integrated semiconductordevices typically contain hundreds to millions of electrical components.Examples of integrated semiconductor devices include microcontrollers,microprocessors, charged-coupled devices (CCDs), solar cells, anddigital micro-mirror devices (DMDs).

Semiconductor devices perform a wide range of functions such as signalprocessing, high-speed calculations, transmitting and receivingelectromagnetic signals, controlling electronic devices, transformingsunlight to electricity, and creating visual projections for televisiondisplays. Semiconductor devices are found in the fields ofentertainment, communications, power conversion, networks, computers,and consumer products. Semiconductor devices are also found in militaryapplications, aviation, automotive, industrial controllers, and officeequipment.

Semiconductor devices exploit the electrical properties of semiconductormaterials. The atomic structure of semiconductor material allows itselectrical conductivity to be manipulated by the application of anelectric field or base current or through the process of doping. Dopingintroduces impurities into the semiconductor material to manipulate andcontrol the conductivity of the semiconductor device.

A semiconductor device contains active and passive electricalstructures. Active structures, including bipolar and field effecttransistors, control the flow of electrical current. By varying levelsof doping and application of an electric field or base current, thetransistor either promotes or restricts the flow of electrical current.Passive structures, including resistors, capacitors, and inductors,create a relationship between voltage and current necessary to perform avariety of electrical functions. The passive and active structures areelectrically connected to form circuits, which enable the semiconductordevice to perform high-speed calculations and other useful functions.

Semiconductor devices are generally manufactured using two complexmanufacturing processes, i.e., front-end manufacturing, and back-endmanufacturing, each involving potentially hundreds of steps. Front-endmanufacturing involves the formation of a plurality of die on thesurface of a semiconductor wafer. Each die is typically identical andcontains circuits formed by electrically connecting active and passivecomponents. Back-end manufacturing involves singulating individual diefrom the finished wafer and packaging the die to provide structuralsupport and environmental isolation.

One goal of semiconductor manufacturing is to produce smallersemiconductor devices. Smaller devices typically consume less power,have higher performance, and can be produced more efficiently. Inaddition, smaller semiconductor devices have a smaller footprint, whichis desirable for smaller end products. A smaller die size may beachieved by improvements in the front-end process resulting in die withsmaller, higher density active and passive components. Back-endprocesses may result in semiconductor device packages with a smallerfootprint by improvements in electrical interconnection and packagingmaterials.

In a conventional fan-out wafer level chip scale package (Fo-WLCSP), asemiconductor die is typically enclosed by an encapsulant. A top andbottom build-up interconnect structure are formed over opposite surfacesof the encapsulant. A redistribution layer (RDL) and insulating layerare commonly formed within the top and bottom build-up interconnectstructures. In addition, a conductive pillar is typically formed throughthe encapsulant for z-direction vertical electrical interconnect betweenthe top and bottom interconnect structures. The conductive pillar andRDL formation are known to use complicated, expensive, andtime-consuming processes involving lithography, etching, and metaldeposition.

SUMMARY OF THE INVENTION

A need exists to provide z-direction vertical electrical interconnectfor a Fo-WLCSP while reducing conductive pillar and RDL formation forlower manufacturing costs. Accordingly, in one embodiment, the presentinvention is a method of making a semiconductor device comprising thesteps of providing a carrier, mounting a first semiconductor die overthe carrier, providing an interposer frame having an opening in theinterposer frame and a plurality of conductive pillars formed over theinterposer frame, mounting the interposer over the carrier and firstsemiconductor die with the conductive pillars disposed around the firstsemiconductor die, depositing an encapsulant through the opening in theinterposer frame over the carrier and first semiconductor die, removingthe carrier, and forming an interconnect structure over the encapsulantand first semiconductor die.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a carrier,mounting a first semiconductor die over the carrier, depositing anencapsulant over the carrier and first semiconductor die, providing aninterposer frame having an opening in the interposer frame and aplurality of conductive pillars formed over the interposer frame,mounting the interposer over the carrier and first semiconductor die bypressing the interposer frame against the encapsulant, removing thecarrier, and forming an interconnect structure over the encapsulant andfirst semiconductor die.

In another embodiment, the present invention is a method of making asemiconductor device comprising the steps of providing a firstsemiconductor die, providing an interposer frame having an opening inthe interposer frame and a plurality of conductive pillars formed overthe interposer frame, mounting the interposer over the firstsemiconductor die with the conductive pillars disposed around the firstsemiconductor die, depositing an encapsulant over the firstsemiconductor die, and forming an interconnect structure over theencapsulant and first semiconductor die.

In another embodiment, the present invention is a semiconductor devicecomprising a first semiconductor die and interposer frame mounted overthe first semiconductor die. The interposer frame has an opening in theinterposer frame and a plurality of conductive pillars formed over theinterposer frame. An encapsulant is deposited over the firstsemiconductor die. An interconnect structure is formed over theencapsulant and first semiconductor die.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a PCB with different types of packages mounted to itssurface;

FIGS. 2 a-2 c illustrate further detail of the representativesemiconductor packages mounted to the PCB;

FIGS. 3 a-3 c illustrate a semiconductor wafer with a plurality ofsemiconductor die separated by saw streets;

FIGS. 4 a-4 f illustrate a pre-formed interposer frame with conductivepillars formed over the interposer frame;

FIGS. 5 a-5 h illustrate a process of forming a Fo-WLCSP with aninterposer frame and conductive pillars providing vertical interconnectfor a semiconductor die;

FIG. 6 illustrates the Fo-WLCSP with the interposer frame and conductivepillars providing vertical interconnect for the semiconductor die;

FIG. 7 illustrates a plurality of stack Fo-WLCSP each with an interposerframe and conductive pillars providing vertical interconnect for thesemiconductor die;

FIGS. 8 a-8 g illustrate mounting the interposer frame over anencapsulant slurry;

FIG. 9 illustrates the Fo-WLCSP with the interposer frame mounted overthe encapsulant slurry;

FIGS. 10 a-10 e illustrate forming the interposer frame with cavities topartially contain the semiconductor die;

FIG. 11 illustrates the Fo-WLCSP with the semiconductor die partiallycontained within the cavities of the interposer frame;

FIG. 12 illustrates the Fo-WLCSP with a bond wire type semiconductor diemounted over the interposer frame; and

FIG. 13 illustrates the Fo-WLCSP with an ISM mounted over thesemiconductor die.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention is described in one or more embodiments in thefollowing description with reference to the figures, in which likenumerals represent the same or similar elements. While the invention isdescribed in terms of the best mode for achieving the invention'sobjectives, it will be appreciated by those skilled in the art that itis intended to cover alternatives, modifications, and equivalents as maybe included within the spirit and scope of the invention as defined bythe appended claims and their equivalents as supported by the followingdisclosure and drawings.

Semiconductor devices are generally manufactured using two complexmanufacturing processes: front-end manufacturing and back-endmanufacturing. Front-end manufacturing involves the formation of aplurality of die on the surface of a semiconductor wafer. Each die onthe wafer contains active and passive electrical components, which areelectrically connected to form functional electrical circuits. Activeelectrical components, such as transistors and diodes, have the abilityto control the flow of electrical current. Passive electricalcomponents, such as capacitors, inductors, resistors, and transformers,create a relationship between voltage and current necessary to performelectrical circuit functions.

Passive and active components are formed over the surface of thesemiconductor wafer by a series of process steps including doping,deposition, photolithography, etching, and planarization. Dopingintroduces impurities into the semiconductor material by techniques suchas ion implantation or thermal diffusion. The doping process modifiesthe electrical conductivity of semiconductor material in active devices,transforming the semiconductor material into an insulator, conductor, ordynamically changing the semiconductor material conductivity in responseto an electric field or base current. Transistors contain regions ofvarying types and degrees of doping arranged as necessary to enable thetransistor to promote or restrict the flow of electrical current uponthe application of the electric field or base current.

Active and passive components are formed by layers of materials withdifferent electrical properties. The layers can be formed by a varietyof deposition techniques determined in part by the type of materialbeing deposited. For example, thin film deposition may involve chemicalvapor deposition (CVD), physical vapor deposition (PVD), electrolyticplating, and electroless plating processes. Each layer is generallypatterned to form portions of active components, passive components, orelectrical connections between components.

The layers can be patterned using photolithography, which involves thedeposition of light sensitive material, e.g., photoresist, over thelayer to be patterned. A pattern is transferred from a photomask to thephotoresist using light. The portion of the photoresist patternsubjected to light is removed using a solvent, exposing portions of theunderlying layer to be patterned. The remainder of the photoresist isremoved, leaving behind a patterned layer. Alternatively, some types ofmaterials are patterned by directly depositing the material into theareas or voids formed by a previous deposition/etch process usingtechniques such as electroless and electrolytic plating.

Depositing a thin film of material over an existing pattern canexaggerate the underlying pattern and create a non-uniformly flatsurface. A uniformly flat surface is required to produce smaller andmore densely packed active and passive components. Planarization can beused to remove material from the surface of the wafer and produce auniformly flat surface. Planarization involves polishing the surface ofthe wafer with a polishing pad. An abrasive material and corrosivechemical are added to the surface of the wafer during polishing. Thecombined mechanical action of the abrasive and corrosive action of thechemical removes any irregular topography, resulting in a uniformly flatsurface.

Back-end manufacturing refers to cutting or singulating the finishedwafer into the individual die and then packaging the die for structuralsupport and environmental isolation. To singulate the die, the wafer isscored and broken along non-functional regions of the wafer called sawstreets or scribes. The wafer is singulated using a laser cutting toolor saw blade. After singulation, the individual die are mounted to apackage substrate that includes pins or contact pads for interconnectionwith other system components. Contact pads formed over the semiconductordie are then connected to contact pads within the package. Theelectrical connections can be made with solder bumps, stud bumps,conductive paste, or wirebonds. An encapsulant or other molding materialis deposited over the package to provide physical support and electricalisolation. The finished package is then inserted into an electricalsystem and the functionality of the semiconductor device is madeavailable to the other system components.

FIG. 1 illustrates electronic device 50 having a chip carrier substrateor printed circuit board (PCB) 52 with a plurality of semiconductorpackages mounted on its surface. Electronic device 50 may have one typeof semiconductor package, or multiple types of semiconductor packages,depending on the application. The different types of semiconductorpackages are shown in FIG. 1 for purposes of illustration.

Electronic device 50 may be a stand-alone system that uses thesemiconductor packages to perform one or more electrical functions.Alternatively, electronic device 50 may be a subcomponent of a largersystem. For example, electronic device 50 may be part of a cellularphone, personal digital assistant (PDA), digital video camera (DVC), orother electronic communication device. Alternatively, electronic device50 can be a graphics card, network interface card, or other signalprocessing card that can be inserted into a computer. The semiconductorpackage can include microprocessors, memories, application specificintegrated circuits (ASIC), logic circuits, analog circuits, RFcircuits, discrete devices, or other semiconductor die or electricalcomponents. The miniaturization and the weight reduction are essentialfor these products to be accepted by the market. The distance betweensemiconductor devices must be decreased to achieve higher density.

In FIG. 1, PCB 52 provides a general substrate for structural supportand electrical interconnect of the semiconductor packages mounted on thePCB. Conductive signal traces 54 are formed over a surface or withinlayers of PCB 52 using evaporation, electrolytic plating, electrolessplating, screen printing, or other suitable metal deposition process.Signal traces 54 provide for electrical communication between each ofthe semiconductor packages, mounted components, and other externalsystem components. Traces 54 also provide power and ground connectionsto each of the semiconductor packages.

In some embodiments, a semiconductor device has two packaging levels.First level packaging is a technique for mechanically and electricallyattaching the semiconductor die to an intermediate carrier. Second levelpackaging involves mechanically and electrically attaching theintermediate carrier to the PCB. In other embodiments, a semiconductordevice may only have the first level packaging where the die ismechanically and electrically mounted directly to the PCB.

For the purpose of illustration, several types of first level packaging,including wire bond package 56 and flip chip 58, are shown on PCB 52.Additionally, several types of second level packaging, including ballgrid array (BGA) 60, bump chip carrier (BCC) 62, dual in-line package(DIP) 64, land grid array (LGA) 66, multi-chip module (MCM) 68, quadflat non-leaded package (QFN) 70, and quad flat package 72, are shownmounted on PCB 52. Depending upon the system requirements, anycombination of semiconductor packages, configured with any combinationof first and second level packaging styles, as well as other electroniccomponents, can be connected to PCB 52. In some embodiments, electronicdevice 50 includes a single attached semiconductor package, while otherembodiments call for multiple interconnected packages. By combining oneor more semiconductor packages over a single substrate, manufacturerscan incorporate pre-made components into electronic devices and systems.Because the semiconductor packages include sophisticated functionality,electronic devices can be manufactured using cheaper components and astreamlined manufacturing process. The resulting devices are less likelyto fail and less expensive to manufacture resulting in a lower cost forconsumers.

FIGS. 2 a-2 c show exemplary semiconductor packages. FIG. 2 aillustrates further detail of DIP 64 mounted on PCB 52. Semiconductordie 74 includes an active region containing analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed within the die and are electricallyinterconnected according to the electrical design of the die. Forexample, the circuit may include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements formedwithin the active region of semiconductor die 74. Contact pads 76 areone or more layers of conductive material, such as aluminum (Al), copper(Cu), tin (Sn), nickel (Ni), gold (Au), or silver (Ag), and areelectrically connected to the circuit elements formed withinsemiconductor die 74. During assembly of DIP 64, semiconductor die 74 ismounted to an intermediate carrier 78 using a gold-silicon eutecticlayer or adhesive material such as thermal epoxy or epoxy resin. Thepackage body includes an insulative packaging material such as polymeror ceramic. Conductor leads 80 and wire bonds 82 provide electricalinterconnect between semiconductor die 74 and PCB 52. Encapsulant 84 isdeposited over the package for environmental protection by preventingmoisture and particles from entering the package and contaminating die74 or wire bonds 82.

FIG. 2 b illustrates further detail of BCC 62 mounted on PCB 52.Semiconductor die 88 is mounted over carrier 90 using an underfill orepoxy-resin adhesive material 92. Wire bonds 94 provide first levelpackaging interconnect between contact pads 96 and 98. Molding compoundor encapsulant 100 is deposited over semiconductor die 88 and wire bonds94 to provide physical support and electrical isolation for the device.Contact pads 102 are formed over a surface of PCB 52 using a suitablemetal deposition process such as electrolytic plating or electrolessplating to prevent oxidation. Contact pads 102 are electricallyconnected to one or more conductive signal traces 54 in PCB 52. Bumps104 are formed between contact pads 98 of BCC 62 and contact pads 102 ofPCB 52.

In FIG. 2 c, semiconductor die 58 is mounted face down to intermediatecarrier 106 with a flip chip style first level packaging. Active region108 of semiconductor die 58 contains analog or digital circuitsimplemented as active devices, passive devices, conductive layers, anddielectric layers formed according to the electrical design of the die.For example, the circuit may include one or more transistors, diodes,inductors, capacitors, resistors, and other circuit elements withinactive region 108. Semiconductor die 58 is electrically and mechanicallyconnected to carrier 106 through bumps 110.

BGA 60 is electrically and mechanically connected to PCB 52 with a BGAstyle second level packaging using bumps 112. Semiconductor die 58 iselectrically connected to conductive signal traces 54 in PCB 52 throughbumps 110, signal lines 114, and bumps 112. A molding compound orencapsulant 116 is deposited over semiconductor die 58 and carrier 106to provide physical support and electrical isolation for the device. Theflip chip semiconductor device provides a short electrical conductionpath from the active devices on semiconductor die 58 to conductiontracks on PCB 52 in order to reduce signal propagation distance, lowercapacitance, and improve overall circuit performance. In anotherembodiment, the semiconductor die 58 can be mechanically andelectrically connected directly to PCB 52 using flip chip style firstlevel packaging without intermediate carrier 106.

FIG. 3 a shows a semiconductor wafer 120 with a base substrate material122, such as silicon, germanium, gallium arsenide, indium phosphide, orsilicon carbide, for structural support. A plurality of semiconductordie or components 124 is formed on wafer 120 separated by saw streets126 as described above.

FIG. 3 b shows a cross-sectional view of a portion of semiconductorwafer 120. Each semiconductor die 124 has a back surface 128 and anactive surface 130 containing analog or digital circuits implemented asactive devices, passive devices, conductive layers, and dielectriclayers formed within the die and electrically interconnected accordingto the electrical design and function of the die. For example, thecircuit may include one or more transistors, diodes, and other circuitelements formed within active surface 130 to implement analog circuitsor digital circuits, such as digital signal processor (DSP), ASIC,memory, or other signal processing circuit. Semiconductor die 124 mayalso contain integrated passive devices (IPD), such as inductors,capacitors, and resistors, for RF signal processing. In one embodiment,semiconductor die 124 is a flipchip type semiconductor die.

An electrically conductive layer 132 is formed over active surface 130using PVD, CVD, electrolytic plating, electroless plating process, orother suitable metal deposition process. Conductive layer 132 can be oneor more layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 132 operates as contact padselectrically connected to the circuits on active surface 130.

In FIG. 3 c, semiconductor wafer 120 is singulated through saw street126 using a saw blade or laser cutting tool 134 into individualsemiconductor die 124.

FIG. 4 a-4 f shows formation of a wafer-form, strip interposer withconductive pillars. In FIG. 4 a, a substrate or carrier 140 containstemporary or sacrificial base material such as silicon, polymer,beryllium oxide, or other suitable low-cost, rigid material forstructural support. An interface layer or double-sided tape 142 isformed over carrier 140 as a temporary adhesive bonding film oretch-stop layer. A semiconductor wafer or substrate 144 contains a basematerial, such as silicon, germanium, gallium arsenide, indiumphosphide, or silicon carbide, for structural support. As asemiconductor wafer, substrate 144 can contain embedded semiconductordie or passive devices. Substrate 144 can also be a multi-layerlaminate, ceramic, or leadframe. Substrate 144 is mounted to interfacelayer 142 over carrier 140.

In FIG. 4 b, a plurality of vias is formed through substrate 144 usinglaser drilling, mechanical drilling, or deep reactive ion etching(DRIE). The vias are filled with Al, Cu, Sn, Ni, Au, Ag, titanium (Ti),tungsten (W), poly-silicon, or other suitable electrically conductivematerial using electrolytic plating, electroless plating process, orother suitable metal deposition process to form z-direction verticalinterconnect conductive vias 146.

An insulating or passivation layer 148 is formed over a surface ofsubstrate 144 and conductive vias 146 using PVD, CVD, printing, spincoating, spray coating, sintering or thermal oxidation. The insulatinglayer 148 contains one or more layers of silicon dioxide (SiO2), siliconnitride (Si3N4), silicon oxynitride (SiON), tantalum pentoxide (Ta2O5),aluminum oxide (Al2O3), or other material having similar insulating andstructural properties. A portion of insulating layer 148 is removed byan etching process to expose substrate 144 and conductive vias 146.

An electrically conductive layer or RDL 150 is formed over the exposedsubstrate 144 and conductive vias 146 using a patterning and metaldeposition process such as printing, PVD, CVD, sputtering, electrolyticplating, and electroless plating. Conductive layer 150 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 150 is electrically connected toconductive vias 146.

In FIG. 4 c, a substrate or carrier 154 contains temporary orsacrificial base material such as silicon, polymer, beryllium oxide, orother suitable low-cost, rigid material for structural support. Aninterface layer or double-sided tape 156 is formed over carrier 154 as atemporary adhesive bonding film or etch-stop layer. Leading withinsulating layer 148 and conductive layer 150, substrate 144 is mountedto interface layer 156 over carrier 154. Carrier 140 and interface layer142 are removed by chemical etching, mechanical peeling, CMP, mechanicalgrinding, thermal bake, UV light, laser scanning, or wet stripping toexpose a surface of substrate 144 and conductive vias 146 oppositeconductive layer 150.

An insulating or passivation layer 158 is formed over substrate 144 andconductive vias 146 using PVD, CVD, printing, spin coating, spraycoating, sintering or thermal oxidation. The insulating layer 158contains one or more layers of Si)2, Si3N4, SiON, Ta2O5, Al2O3, or othermaterial having similar insulating and structural properties. A portionof insulating layer 158 is removed by an etching process to exposesubstrate 144 and conductive vias 146.

An electrically conductive layer or RDL 160 is formed over the exposedsubstrate 144 and conductive vias 146 using a patterning and metaldeposition process such as printing, PVD, CVD, sputtering, electrolyticplating, and electroless plating. Conductive layer 160 can be one ormore layers of Al, Cu, Sn, Ni, Au, Ag, or other suitable electricallyconductive material. Conductive layer 160 is electrically connected toconductive vias 146.

In another embodiment, conductive vias 146 are formed through substrate144 after forming conductive layers 150 and/or 160.

In FIG. 4 d, a photoresist layer 162 is formed over insulating layer 158and conductive layer 160. A plurality of vias is formed throughphotoresist layer 162 over conductive layer 160 using a patterning andetching process. The vias are filled with Al, Cu, Sn, Ni, Au, Ag, Ti, W,poly-silicon, or other suitable electrically conductive material usingelectrolytic plating, electroless plating process, or other suitablemetal deposition process. Stacked bumps and stud bumps can also beformed in the vias.

In FIG. 4 e, photoresist layer 162 is removed leaving z-directionvertical interconnect conductive pillars 164 over conductive layer 160.Carrier 154 and interface layer 156 are removed by chemical etching,mechanical peeling, CMP, mechanical grinding, thermal bake, UV light,laser scanning, or wet stripping leaving the pre-formed interposer frame166 with conductive pillars 164. Conductive layers 150 and 160 andconductive vias 146 constitute a vertical interconnect formed throughinterposer frame 166. One or more openings 168 are formed throughinterposer frame 166. FIG. 4 f shows a top view of interposer frame 166with conductive pillars 164 and openings 168.

FIGS. 5 a-5 h illustrate, in relation to FIGS. 1 and 2 a-2 c, a processof forming a Fo-WLCSP with an interposer frame and conductive pillarsproviding vertical interconnect for a semiconductor die. In FIG. 5 a, asubstrate or carrier 170 contains temporary or sacrificial base materialsuch as silicon, polymer, beryllium oxide, or other suitable low-cost,rigid material for structural support. An interface layer ordouble-sided tape 171 is formed over carrier 170 as a temporary adhesivebonding film or etch-stop layer.

In FIG. 5 b, semiconductor die 124 from FIGS. 3 a-3 c are mounted overinterface layer 171. In particular, semiconductor die 124 are mounted tointerface layer 171 with active surface 130 oriented toward carrier 170.

In FIG. 5 c, the pre-formed interposer frame 166 is positioned overcarrier 170. The interposer frame 166 is mounted to interface layer 171with conductive pillars 164 disposed around semiconductor die 124, asshown in FIG. 5 d. Alignment marks 173 can be made on interface layer171 to assist with mounting interposer frame 166. Solder paste can alsobe deposited on carrier 170 to assist with alignment and bonding ofinterposer frame 166 to the carrier. The height of conductive pillars164 is greater than a thickness of semiconductor die 124. Accordingly, agap remains between back surface 128 of semiconductor die 124 andinterposer frame 166.

In FIG. 5 e, an encapsulant or molding compound 172 is injected ordeposited through openings 168 around semiconductor die 124 and in thegap between interposer frame 166 and the die using a paste printing,compressive molding, transfer molding, liquid encapsulant molding,vacuum lamination, spin coating, or other suitable applicator.Encapsulant 172 can be polymer composite material, such as epoxy resinwith filler, epoxy acrylate with filler, or polymer with proper filler.Encapsulant 172 is non-conductive and environmentally protects thesemiconductor device from external elements and contaminants.Semiconductor die 124 can be mounted to wettable contact pads formedover carrier 170 to reduce die shifting during encapsulation.

In FIG. 5 f, carrier 170 and interface layer 171 are removed by chemicaletching, mechanical peeling, CMP, mechanical grinding, thermal bake, UVlight, laser scanning, or wet stripping to expose encapsulant 172,semiconductor die 124, and conductive pillars 164.

In FIG. 5 g, a build-up interconnect structure 174 is formed oversemiconductor die 124, conductive pillars 164, and encapsulant 172. Thebuild-up interconnect structure 174 includes an electrically conductivelayer or RDL 176 formed using a patterning and metal deposition processsuch as sputtering, electrolytic plating, and electroless plating.Conductive layer 176 can be one or more layers of Al, Cu, Sn, Ni, Au,Ag, or other suitable electrically conductive material. One portion ofconductive layer 176 is electrically connected to contact pads 132 ofsemiconductor die 124. Another portion of conductive layer 176 iselectrically connected to conductive pillars 164. Other portions ofconductive layer 176 can be electrically common or electrically isolateddepending on the design and function of semiconductor die 124.

An insulating or passivation layer 178 is formed around conductive layer176 for electrical isolation using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. The insulating layer 178contains one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, or othermaterial having similar insulating and structural properties. A portionof insulating layer 178 can be removed by an etching process to exposeconductive layer 176 for additional electrical interconnect.

In FIG. 5 h, an electrically conductive bump material is deposited overbuild-up interconnect structure 174 and electrically connected to theexposed portion of conductive layer 176 using an evaporation,electrolytic plating, electroless plating, ball drop, or screen printingprocess. The bump material can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu,solder, and combinations thereof, with an optional flux solution. Forexample, the bump material can be eutectic Sn/Pb, high-lead solder, orlead-free solder. The bump material is bonded to conductive layer 176using a suitable attachment or bonding process. In one embodiment, thebump material is reflowed by heating the material above its meltingpoint to form spherical balls or bumps 180. In some applications, bumps180 are reflowed a second time to improve electrical contact toconductive layer 176. An under bump metallization (UBM) can be formedunder bumps 180. The bumps can also be compression bonded to conductivelayer 176. Bumps 180 represent one type of interconnect structure thatcan be formed over conductive layer 176. The interconnect structure canalso use stud bump, micro bump, or other electrical interconnect.

Semiconductor die 124 are singulated through interposer frame 166,encapsulant 172, and build-up interconnect structure 174 with saw bladeor laser cutting tool 182 into individual Fo-WLCSP 184. FIG. 6 showsFo-WLCSP 184 after singulation. Semiconductor die 124 is electricallyconnected through contact pads 132 and build-up interconnect structure174 to conductive pillars 164 and interposer frame 166. The pre-formedinterposer frame 166 simplifies the assembly process by negating theneed for RDL patterning over at least one surface of encapsulant 172, orforming conductive pillars through the encapsulant.

FIG. 7 shows a plurality of stacked Fo-WLCSP 184 electrically connectedthrough interposer frame 166, build-up interconnect structure 174, bumps180, and conductive vias 164.

FIGS. 8 a-8 g illustrate, in relation to FIGS. 1 and 2 a-2 c, anotherprocess of forming a Fo-WLCSP with an interposer frame and conductivepillars providing vertical interconnect for a semiconductor die. In FIG.8 a, a substrate or carrier 190 contains temporary or sacrificial basematerial such as silicon, polymer, beryllium oxide, or other suitablelow-cost, rigid material for structural support. An interface layer ordouble-sided tape 192 is formed over carrier 190 as a temporary adhesivebonding film or etch-stop layer.

Semiconductor die 124 from FIG. 3 a-3 c are mounted over interface layer192. In particular, semiconductor die 124 are mounted to interface layer192 with active surface 130 oriented toward carrier 190.

In FIG. 8 b, an encapsulant or molding compound 194 is deposited overcarrier 190 and semiconductor die 124 as a slurry. Encapsulant slurry194 can be polymer composite material, such as epoxy resin with filler,epoxy acrylate with filler, or polymer with proper filler.

In FIG. 8 c, the pre-formed interposer frame 166 from FIGS. 4 a-4 f ispositioned over carrier 190. The interposer frame 166 is mounted tointerface layer 192 by pressing the interposer frame onto encapsulantslurry 194 with force F. The pressure from force F causes encapsulantslurry 194 to flatten and completely fill the area under interposerframe 166 around semiconductor die 124 and conductive pillars 164.Excess encapsulant slurry 194 exits through openings 168.

When properly seated, conductive pillars 164 are disposed aroundsemiconductor die 124 and contacting interface layer 192, as shown inFIG. 8 d. Encapsulant 194 surrounds semiconductor die 124 and conductivepillars 164. The height of conductive pillars 164 is greater than athickness of semiconductor die 124. Accordingly, back surface 128 ofsemiconductor die 124 is covered by encapsulant 194. Semiconductor die124 can be mounted to wettable contact pads formed over carrier 190 toreduce die shifting during encapsulation.

In FIG. 8 e, carrier 190 and interface layer 192 are removed by chemicaletching, mechanical peeling, CMP, mechanical grinding, thermal bake, UVlight, laser scanning, or wet stripping to expose encapsulant 194,semiconductor die 124, and conductive pillars 164.

In FIG. 8 f, a build-up interconnect structure 196 is formed oversemiconductor die 124, conductive pillars 164, and encapsulant 194. Thebuild-up interconnect structure 196 includes an electrically conductivelayer or RDL 198 formed using a patterning and metal deposition processsuch as sputtering, electrolytic plating, and electroless plating.Conductive layer 198 can be one or more layers of Al, Cu, Sn, Ni, Au,Ag, or other suitable electrically conductive material. One portion ofconductive layer 198 is electrically connected to contact pads 132 ofsemiconductor die 124. Another portion of conductive layer 198 iselectrically connected to conductive pillars 164. Other portions ofconductive layer 198 can be electrically common or electrically isolateddepending on the design and function of semiconductor die 124.

An insulating or passivation layer 200 is formed around conductive layer198 for electrical isolation using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. The insulating layer 200contains one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, or othermaterial having similar insulating and structural properties. A portionof insulating layer 200 can be removed by an etching process to exposeconductive layer 198 for additional electrical interconnect.

In FIG. 8 g, an electrically conductive bump material is deposited overbuild-up interconnect structure 196 and electrically connected to theexposed portion of conductive layer 198 using an evaporation,electrolytic plating, electroless plating, ball drop, or screen printingprocess. The bump material can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu,solder, and combinations thereof, with an optional flux solution. Forexample, the bump material can be eutectic Sn/Pb, high-lead solder, orlead-free solder. The bump material is bonded to conductive layer 198using a suitable attachment or bonding process. In one embodiment, thebump material is reflowed by heating the material above its meltingpoint to form spherical balls or bumps 202. In some applications, bumps202 are reflowed a second time to improve electrical contact toconductive layer 198. A UBM can be formed under bumps 202. The bumps canalso be compression bonded to conductive layer 198. Bumps 202 representone type of interconnect structure that can be formed over conductivelayer 198. The interconnect structure can also use stud bump, microbump, or other electrical interconnect.

Semiconductor die 124 are singulated through interposer frame 166,encapsulant 194, and build-up interconnect structure 196 with saw bladeor laser cutting tool 204 into individual Fo-WLCSP 206. FIG. 9 showsFo-WLCSP 206 after singulation. Semiconductor die 124 is electricallyconnected through contact pads 132 and build-up interconnect structure196 to conductive pillars 164 and interposer frame 166. The pre-formedinterposer frame 166 simplifies the assembly process by negating theneed for RDL patterning over at least one surface of encapsulant 194, orforming conductive pillars through the encapsulant. Depositingencapsulant slurry 194 prior to mounting interposer frame 166 and thenpressing the interposer frame over the encapsulant slurry providesuniform coverage of the encapsulant around semiconductor die 124 andconductive pillars 164.

FIGS. 10 a-10 e illustrate, in relation to FIGS. 1 and 2 a-2 c, anotherprocess of forming a Fo-WLCSP with an interposer frame and conductivepillars providing vertical interconnect for a semiconductor die.Continuing from FIG. 8 b, a pre-formed interposer frame 210 ispositioned over carrier 190, as shown in FIG. 10 a. In this case,interposer frame 210 has cavities or recesses 212 formed in substrate214 in areas designated for alignment with semiconductor die 124.Conductive vias and layers 215 are formed through substrate 214 andinsulating layer 217 similar to FIGS. 4 a-4 f. One or more openings 216are formed through interposer frame 210. The interposer frame 210 ismounted to interface layer 192 by pressing the interposer frame ontoencapsulant slurry 194 with force F. The pressure from force F causesencapsulant slurry 194 to flatten and completely fill the area underinterposer frame 210 and around semiconductor die 124 and conductivepillars 218. Excess encapsulant slurry 194 exits through openings 216.

When properly seated, semiconductor die 124 are partially disposedwithin cavities 212. Conductive pillars 218 are disposed aroundsemiconductor die 124 and contacting interface layer 192, as shown inFIG. 10 b. Encapsulant 194 surrounds semiconductor die 124 andconductive pillars 164. Semiconductor die 124 can be mounted to wettablecontact pads formed over carrier 190 to reduce die shifting duringencapsulation.

In FIG. 10 c, carrier 190 and interface layer 192 are removed bychemical etching, mechanical peeling, CMP, mechanical grinding, thermalbake, UV light, laser scanning, or wet stripping to expose encapsulant194, semiconductor die 124, and conductive pillars 218.

In FIG. 10 d, a build-up interconnect structure 222 is formed oversemiconductor die 124, conductive pillars 218, and encapsulant 194. Thebuild-up interconnect structure 222 includes an electrically conductivelayer or RDL 224 formed using a patterning and metal deposition processsuch as sputtering, electrolytic plating, and electroless plating.Conductive layer 224 can be one or more layers of Al, Cu, Sn, Ni, Au,Ag, or other suitable electrically conductive material. One portion ofconductive layer 224 is electrically connected to contact pads 132 ofsemiconductor die 124. Another portion of conductive layer 224 iselectrically connected to conductive pillars 218. Other portions ofconductive layer 224 can be electrically common or electrically isolateddepending on the design and function of semiconductor die 124.

An insulating or passivation layer 226 is formed around conductive layer226 for electrical isolation using PVD, CVD, printing, spin coating,spray coating, sintering or thermal oxidation. The insulating layer 226contains one or more layers of SiO2, Si3N4, SiON, Ta2O5, Al2O3, or othermaterial having similar insulating and structural properties. A portionof insulating layer 226 can be removed by an etching process to exposeconductive layer 224 for additional electrical interconnect.

In FIG. 10 e, an electrically conductive bump material is deposited overbuild-up interconnect structure 222 and electrically connected to theexposed portion of conductive layer 224 using an evaporation,electrolytic plating, electroless plating, ball drop, or screen printingprocess. The bump material can be Al, Sn, Ni, Au, Ag, Pb, Bi, Cu,solder, and combinations thereof, with an optional flux solution. Forexample, the bump material can be eutectic Sn/Pb, high-lead solder, orlead-free solder. The bump material is bonded to conductive layer 224using a suitable attachment or bonding process. In one embodiment, thebump material is reflowed by heating the material above its meltingpoint to form spherical balls or bumps 228. In some applications, bumps228 are reflowed a second time to improve electrical contact toconductive layer 224. A UBM can be formed under bumps 228. The bumps canalso be compression bonded to conductive layer 224. Bumps 228 representone type of interconnect structure that can be formed over conductivelayer 224. The interconnect structure can also use stud bump, microbump, or other electrical interconnect.

Semiconductor die 124 are singulated through interposer frame 210,encapsulant 194, and build-up interconnect structure 196 with saw bladeor laser cutting tool 230 into individual Fo-WLCSP 232. FIG. 11 showsFo-WLCSP 232 after singulation. Semiconductor die 124 is electricallyconnected through contact pads 132 and build-up interconnect structure222 to conductive pillars 218 and interposer frame 210. The pre-formedinterposer frame 210 simplifies the assembly process by negating theneed for RDL patterning over at least one surface of encapsulant 194, orforming conductive pillars through the encapsulant. Depositingencapsulant slurry 194 prior to mounting interposer frame 210 and thenpressing the interposer frame over the encapsulant slurry providesuniform coverage of the encapsulant around semiconductor die 124.Cavities 212 reduce the height of Fo-WLCSP 232.

FIG. 12 shows an embodiment of Fo-WLCSP 240, similar to FIG. 6, withsemiconductor die 242 mounted to interposer frame 166 with die attachadhesive 244. Semiconductor die 242 has an active surface 248 containinganalog or digital circuits implemented as active devices, passivedevices, conductive layers, and dielectric layers formed within the dieand electrically interconnected according to the electrical design andfunction of the die. For example, the circuit may include one or moretransistors, diodes, and other circuit elements formed within activesurface 248 to implement analog circuits or digital circuits, such asDSP, ASIC, memory, or other signal processing circuit. Semiconductor die242 may also contain IPDs, such as inductors, capacitors, and resistors,for RF signal processing. In one embodiment, semiconductor die 242 is awire-bond die. Bond wires 250 are electrically connected between contactpads 252 on active surface 248 and conductive layer 150 of interposerframe 166.

An encapsulant or molding compound 254 is deposited over semiconductordie 242 and interposer frame 166 using a paste printing, compressivemolding, transfer molding, liquid encapsulant molding, vacuumlamination, spin coating, or other suitable applicator. Encapsulant 254can be polymer composite material, such as epoxy resin with filler,epoxy acrylate with filler, or polymer with proper filler. Encapsulant254 is non-conductive and environmentally protects the semiconductordevice from external elements and contaminants.

FIG. 13 shows an embodiment of Fo-WLCSP 260, similar to FIG. 6, withinternal stacking module (ISM) 262 mounted to semiconductor die 124 withdie attach adhesive 263 prior to mounting interposer frame 166 in FIG. 5c. The internal stacking module 262 includes semiconductor die 264 withan active surface 268 containing analog or digital circuits implementedas active devices, passive devices, conductive layers, and dielectriclayers formed within the die and electrically interconnected accordingto the electrical design and function of the die. For example, thecircuit may include one or more transistors, diodes, and other circuitelements formed within active surface 268 to implement analog circuitsor digital circuits, such as DSP, ASIC, memory, or other signalprocessing circuit. Semiconductor die 264 may also contain IPDs, such asinductors, capacitors, and resistors, for RF signal processing.Semiconductor die 264 is mounted to interposer frame 166 with die attachadhesive 269. Bond wires 270 are electrically connected between contactpads 272 on active surface 268 and conductive layer 160 of interposerframe 166.

An encapsulant or molding compound 274 is deposited over semiconductordie 264 and interposer frame 166 using a paste printing, compressivemolding, transfer molding, liquid encapsulant molding, vacuumlamination, spin coating, or other suitable applicator. Encapsulant 274can be polymer composite material, such as epoxy resin with filler,epoxy acrylate with filler, or polymer with proper filler. Encapsulant274 is non-conductive and environmentally protects the semiconductordevice from external elements and contaminants.

While one or more embodiments of the present invention have beenillustrated in detail, the skilled artisan will appreciate thatmodifications and adaptations to those embodiments may be made withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

1. A method of making a semiconductor device, comprising: providing acarrier; mounting a first semiconductor die over the carrier; providingan interposer frame including an opening in the interposer frame and aplurality of conductive pillars formed over the interposer frame;mounting the interposer frame over the carrier and first semiconductordie including disposing the conductive pillars around the firstsemiconductor die; depositing an encapsulant through the opening in theinterposer frame and over the carrier and first semiconductor die;removing the carrier; and forming an interconnect structure over theencapsulant and first semiconductor die.
 2. The method of claim 1,further including forming a cavity in the interposer frame to contain aportion of the first semiconductor die.
 3. The method of claim 1,further including forming alignment marks over the carrier to assistwith mounting the interposer frame.
 4. The method of claim 1, furtherincluding mounting a second semiconductor die over the firstsemiconductor die prior to depositing the encapsulant.
 5. The method ofclaim 1, further including mounting a second semiconductor die over theinterposer frame.
 6. The method of claim 5, further including forming abond wire between the second semiconductor die and the interposer frame.7. A method of making a semiconductor device, comprising: providing acarrier; mounting a first semiconductor die over the carrier; depositingan encapsulant over the carrier and first semiconductor die; providingan interposer frame including an opening in the interposer frame and aplurality of conductive pillars formed over the interposer frame;mounting the interposer frame over the carrier and first semiconductordie by pressing the interposer frame against the encapsulant; removingthe carrier; and forming an interconnect structure over the encapsulantand first semiconductor die.
 8. The method of claim 7, wherein excessencapsulant exits through the opening in the interposer frame.
 9. Themethod of claim 7, wherein the conductive pillars are disposed aroundthe first semiconductor die.
 10. The method of claim 7, furtherincluding forming a cavity in the interposer frame to contain a portionof the first semiconductor die.
 11. The method of claim 7, furtherincluding mounting a second semiconductor die over the firstsemiconductor die prior to depositing the encapsulant.
 12. The method ofclaim 7, further including mounting a second semiconductor die over theinterposer frame.
 13. The method of claim 12, further including forminga bond wire between the second semiconductor die and the interposerframe.
 14. A method of making a semiconductor device, comprising:providing a first semiconductor die; providing an interposer frameincluding an opening in the interposer frame and a plurality ofconductive pillars formed over the interposer frame; mounting theinterposer frame over the first semiconductor die including disposingthe conductive pillars around the first semiconductor die; depositing anencapsulant over the first semiconductor die; and forming aninterconnect structure over the encapsulant and first semiconductor die.15. The method of claim 14, further including: depositing theencapsulant over the first semiconductor die prior to mounting theinterposer frame; and pressing the interposer frame against theencapsulant.
 16. The method of claim 15, wherein excess encapsulantexits through the opening in the interposer frame.
 17. The method ofclaim 14, further including depositing the encapsulant through theopening in the interposer frame over the first semiconductor die. 18.The method of claim 14, further including forming a cavity in theinterposer frame to contain a portion of the first semiconductor die.19. The method of claim 14, further including mounting a secondsemiconductor die over the first semiconductor die prior to depositingthe encapsulant.
 20. The method of claim 14, further including mountinga second semiconductor die over the interposer frame.